<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>
        .box{
            width: 400px;
            height: 400px;
            border: 2px dashed violet;
            display: flex;
            margin: 0 auto;
            transform-style: preserve-3d;
            transform: rotateY(0deg);
            background-color: palegreen;
        }
        .center{
            margin: auto;
            width: 100px;
            height: 100px;
            background-color: skyblue;
            transform: rotateX(0deg);
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="center"></div>
    </div>
</body>
</html>